ChemicalBook CAS DataBase List 4,6-Difluoroindole-2-carboxylic acid

4,6-Difluoroindole-2-carboxylic acid synthesis

4synthesis methods

Product Name:4,6-Difluoroindole-2-carboxylic acid
CAS Number:247564-66-5
Molecular formula:C9H5F2NO2
Molecular Weight:197.14

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Yield:-

Reaction Conditions:

Stage #1: ethyl 4,6-difluoro-1H-indole-2-carboxylatewith sodium hydroxide;water in ethanol; for 0.25 h;Heating / reflux;
Stage #2: with hydrogenchloride in water;

Steps:

3.3

A mixture of the above compound (3.48 g) in a 4 N aqueous sodium hydroxide solution (7.73 ml) and ethyl alcohol (35 ml) was refluxed for 15 minutes, and the organic solvent was evaporated under reduced pressure. Thereto was added water, and the mixture was washed with ethyl ether followed by being acidified with a 6 N aqueous hydrochloric acid solution. The resultant mixture was extracted with ethyl acetate, and the organic layer was washed with brine, dried over magnesium sulfate and treated with activated carbon. The insoluble materials were filtered off, and the filtrate was evaporated under reduced pressure to give crude 4,6-difluoro-indole-2-carboxylic acid (3.01 g) as a pale brown solid. mp 253-254 (dec.). ESI-Mass m/Z 196 (M-H).

References:

US2008/27122,2008,A1 Location in patent:Page/Page column 11